Hi Kimberly,
I hope you are well today and thanks for posting here.
It’s not actually the bug as the id attribute is not required if the theme is developed using HTML5 and we have developed Sparkling theme using HTML5.
You can find the default WordPress code to display search form as following in this WordPress core file https://core.trac.www.ads-software.com/browser/tags/4.3.1/src/wp-includes/general-template.php
if ( 'html5' == $format ) {
$form = '<form role="search" method="get" class="search-form" action="' . esc_url( home_url( '/' ) ) . '">
<label>
<span class="screen-reader-text">' . _x( 'Search for:', 'label' ) . '</span>
<input type="search" class="search-field" placeholder="' . esc_attr_x( 'Search …', 'placeholder' ) . '" value="' . get_search_query() . '" name="s" title="' . esc_attr_x( 'Search for:', 'label' ) . '" />
</label>
<input type="submit" class="search-submit" value="'. esc_attr_x( 'Search', 'submit button' ) .'" />
</form>';
} else {
$form = '<form role="search" method="get" id="searchform" class="searchform" action="' . esc_url( home_url( '/' ) ) . '">
<div>
<label class="screen-reader-text" for="s">' . _x( 'Search for:', 'label' ) . '</label>
<input type="text" value="' . get_search_query() . '" name="s" id="s" />
<input type="submit" id="searchsubmit" value="'. esc_attr_x( 'Search', 'submit button' ) .'" />
</div>
</form>';
}
Best Regards,
Movin